JPH0788470A - Deaerator - Google Patents

Abstract

PURPOSE:To efficiently deaerate supplied water by eliminating trouble caused by that the flow of the supplied water in a water storage part doest not become constant. CONSTITUTION:A large number of baffle plates forming a meandering passage 11 toward a supplied water outlet 6 are arranged in a water storage part 4. Two buffle plates 12 constitute one set and one of them is provided so as to follow the extending direction of a bubbling nozzle 5 from a steam header 8 and the other one of them is provided so as to follow the extending direction of the bubbling nozzle 5 in the same way from the inner surface of a shell 1.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a deaerator used for separating and removing dissolved oxygen from feedwater flowing through a boiler feedwater system such as a thermal power plant.

[0002]

2. Description of the Related Art Since the amount of dissolved oxygen in boiler feedwater is deeply related to the corrosion phenomenon in the boiler, most of the power supply systems of thermal power plants have a deaerator for separating and extracting dissolved oxygen in the feedwater by steam heating. Is provided. Generally, such deaerators are often configured as a single unit,
A deaerator may be installed in the condenser.

The basic principle of this degassing is mass diffusion induced by concentration disequilibrium. This is because the higher the nonequilibrium degree, the faster the mass transfer rate, and the shorter the migration distance due to diffusion, the faster the mass speed. Therefore, most of the structures used in the conventional deaerator are designed to increase the contact area by stirring the feed water and making the feed water finer.

FIG. 13 shows an example of a conventional bubbling type deaerator. The water supply enters the vessel through a water supply inlet 2 provided at the top of the shell 1 and is sprayed from a spray 3. This water supply collects in the water storage section 4 in the shell 1 and flows outside the bubbling nozzle 5 toward the water supply outlet 6, and is heated during this time and flows out from the water supply outlet 6.

On the other hand, the steam enters the steam header 8 extending from the steam inlet 7 in the longitudinal direction of the shell 1 and is distributed to the bubbling nozzles 5 each having a large number of through holes. This vapor is jetted from the through hole of the bubbling nozzle 5 to the water storage part 4 and ascends in the feed water, directly contacts the feed water, heats the feed water, and degasses dissolved oxygen. The steam further rises and reaches the steam heating unit 9, which directly contacts and heats the feed water ejected from the spray 3 and degass it, and degass it from the ventro 10 together with the separated oxygen to the outside of the device. leak.

[0006]

In the above-mentioned bubbling type deaerator, the flow of the water supply in the water storage section 4 is the water supply inlet 2
From the water supply outlet 6 to the water supply outlet 6 and the local flow accompanied by the turbulence that the steam ejected from the bubbling nozzle 5 stirs the water supply, and a constant flow path is not maintained.

Degassing progresses in each of the plurality of bubbling nozzles 5, and the majority of the water supply, which was initially in a high oxygen concentration state, is gradually degassed and its concentration decreases until it reaches the water supply outlet 6. Go, but always bubbling nozzle 5
Because the flow is disturbed by the steam ejected from,
For example, feed water once having a low concentration may be carried to the feed water inlet 2 side having a high oxygen concentration, or conversely, feed water having a high oxygen concentration may be carried to the feed water outlet 6 without being deaerated. Due to such uncertainty of the flow path, a special operation is required to keep the dissolved oxygen concentration distribution in the deaerator uniform, and for example, a fixed value required by the boiler side for the dissolved oxygen concentration (hereinafter referred to as the required concentration) ) There is an inconvenience that it takes a long time to decrease the temperature to below.

Further, the bubbles mixed in the water supply may not be extracted and may flow to the equipment of the water supply system, such as a water supply pump, together with the water supply, which may adversely affect the equipment.

Therefore, an object of the present invention is to provide a deaerator capable of efficiently deaerating the water supply by eliminating the inconvenience caused by the inconstant flow of the water supply in the water storage section.

[0010]

In order to achieve the above-mentioned object, the present invention comprises a jetting means consisting of a plurality of nozzles having a large number of through holes communicating with a steam header, and each through hole of the nozzle is shelled. In the degassing device, in which the heated steam guided from the steam header to the nozzle is ejected into the water supply through the through hole, the water supplied to the water storage follows the route determined through the water supply outlet. It is characterized in that the meandering flow path is formed so as to come into contact with the heated steam blown out from the through hole of the nozzle.

[0011]

The present invention considers that, due to the uncertainty of the flow path in the water storage portion of the deaerator, for example, the feed water having a high dissolved oxygen concentration is carried to the feed water outlet without sufficiently contacting the heated steam. A stationary channel is formed in the part. That is, a meandering flow path is formed in which the feed water sent to the water reservoir is brought into contact with the heating steam blown out from the nozzle according to a route determined from the feed outlet. Normally, the steam blown out from the bubbling nozzle placed in the path rises up in the feed water as bubbles, but the flow path constituent member is such that the flow direction of the feed water to the steam bubbles is countercurrent or parallel flow. To place. At this time, the water supply flows while meandering through the flow path formed by the flow path constituent member, and is effectively heated before reaching the water supply outlet. For example, in the case of forming a flow path that is a counter flow, the vapor bubbles achieve an upward movement against the downward flow of the feed water,
The rising speed slows down, it takes time to pass through the water supply, and the contact time between the steam bubbles and the water supply becomes long. As a result, the temperature rise of the feed water is significantly quickened, and the degassing efficiency can be greatly improved. Therefore, the feed water can be degassed without wasting the process steam used as the heating steam.

On the other hand, the feed water flows according to a predetermined route, and the dissolved oxygen concentration decreases every time it comes into contact with the heated steam. For this reason, unlike the conventional device, it is possible to reduce the required concentration in a short time without the water supplies having different dissolved oxygen concentrations being mixed. This brings an advantage that the demand can be easily met, for example, when the boiler start-up time is desired to be shortened.

FIG. 2 shows the transition of the dissolved oxygen concentration according to the present invention in comparison with that according to the prior art. The curve a showing the dissolved oxygen concentration distribution of the present invention is compared with the curve b showing the distribution of the prior art. It can be seen that the gradient is large and the required concentration can be lowered in a short time.

[0014]

Embodiments of the present invention will be described below with reference to the drawings. In FIG. 1 (a), a large number of baffle plates 12 that form a meandering flow path 11 toward a water supply outlet 6 are provided in a water storage section 4 in the shell 1. The baffle plate 12 of the present embodiment includes one set fixed to the inner side of the shell 1 and one set fixed to the steam header 8 as one set, and is composed of a plurality of bubbling nozzles 5 (see FIG. 1B). It is arranged corresponding to the ejection means. That is, of the set of baffle plates 12, the one on the steam header 8 side is extended in the extending direction of the bubbling nozzle 5 to have substantially the same length, and the one having one shell is also formed in the extending direction of the bubbling nozzle 5. It is designed to extend near the upper surface of the water storage section 4.

The main constitution of the water supply system other than the above points is basically the same as the constitution according to the prior art. Moreover, the configuration of the heating steam system is basically the same as that of the conventional technique.

Next, the operation of the deaerator having the above structure will be described.

Water supply enters the vessel through the water supply inlet 2 and is sprayed onto the steam heating section 9 by the spray 3. At this time, the feed water becomes finer, becomes fine water droplets and is heated by contacting the steam filling the space, the temperature rises, and a part reaches the saturation temperature, and dissolved oxygen is separated.

The steam is blown out from the through holes of the bubbling nozzle 5 to become steam bubbles, which meander through the water reservoir 4 to heat the water while rising. Due to this heating, the temperature of the feed water rises, and when the saturation temperature is reached, dissolved oxygen is degassed.

At this time, the flow of the feed water along the baffle plate 12 is a downward flow with respect to the vapor bubbles rising in the feed water, and the vapor bubbles ascend against the flow of the opposing feed water. Becomes slow and it takes time to pass through the water supply. Therefore, the contact time between the steam bubbles and the water supply becomes longer, and the water supply can be effectively heated. Thereafter, the steam bubbles enter the steam heating section 9 through the boundary surface between the water storage section 4 and the steam heating section 9, and fill the space.

As described above, in the deaerator having the above-described structure, when the feed water flows through the water storage section 4, it flows opposite to the vapor bubbles in each part of the meandering flow path 11, and the contact time becomes longer, so that the contact time becomes longer. The temperature rise of the feed water is accelerated, and the degassing efficiency can be greatly improved. Therefore, the process steam used for heating is not wasted. Further, the feed water comes into contact with the heating steam according to the determined route, and the dissolved oxygen concentration decreases each time, and the dissolved oxygen concentration can be lowered to the required temperature in a short time. Also, since the water supply containing steam bubbles is made to flow over the surface of the water storage part, as soon as the steam bubbles reach the boundary surface between the steam heating part and the water storage part during the water supply flow, they are separated from the water supply to the steam heating part. There is no possibility that it will be discharged from the deaerator as it is mixed and not extracted from the water supply.

Further, another embodiment of the present invention will be described with reference to FIG. The present embodiment is similar to the above embodiment in that the feed water comes into contact with the heating steam according to the determined route, but the set of baffle plates 12 for the jetting means by the bubbling nozzle 5 uses the heating steam for the upward flow of the feed water. It is provided to match the flow of. In the present embodiment, the steam bubbles blown into the water supply through the through holes of the bubbling nozzle 5 flow in the same direction as the water supply, that is, as an upward flow, to the boundary surface between the water storage part 4 and the steam heating part 9. The vapor bubbles flowing in the same direction as the water supply, that is, in the parallel flow, give flow energy to the water supply and have a function of keeping the flow of the water supply in the water storage section 4 stable.

Furthermore, an embodiment different from the above is shown in FIG.
Will be described with reference to. In this embodiment, instead of arranging a set of baffle plates 12 in each row of bubbling nozzles 5, a minimum number of baffle plates 12 corresponding to ejection means (7 steps in the embodiment) (however, the spare baffle plate 1 is used). (Excluding the number of sheets), the meandering flow path 11 is formed. The meandering flow passage 11 formed by the small number of baffle plates 12 is a mixture of the feed water and the steam bubbles in the above two embodiments that flow in the counter flow and the flow that flows in the parallel flow. In this embodiment, opposite flow portions and parallel flow portions are formed alternately.

As a result, it is possible to maintain good degassing efficiency in the counter flow portion while stabilizing the flow in the parallel flow portion.

Further, another embodiment will be described with reference to FIG. The meandering flow path 11 of this embodiment is the same as that of the embodiment of FIG. 4 described above, but here the steam header 8 is the water reservoir 4
The steam header 8 is provided with bubbling nozzles 5 that extend horizontally toward the inner wall of the shell 1 near the center of the bottom of the shell. The operation of this embodiment is almost the same as that of FIG.

Although each of the above-described embodiments has a great effect on the improvement of the deaeration performance of the deaeration device, another function is added.

FIG. 6 shows a preferred embodiment for shortening the start-up time and reducing the amount of process steam used. An oxygen concentration meter 13 for detecting the dissolved oxygen concentration and a thermometer 14 for detecting the feed water temperature are respectively provided in the respective portions of the meandering flow path 11, and the output of the oxygen concentration signal and the temperature signal is the amount of heating steam flowing to the steam header 8. Is input to the adjuster 15 for adjusting. Further, a control valve 16 is provided in the steam path connected to the steam header 8, and its opening is adjusted by a control signal given from the controller 15.

For effective degassing, it is necessary to quickly raise the feed water to the saturation temperature, and it is preferable to supply heated steam in consideration of the temperature distribution. As shown in FIG. 7, in the feed water temperature distribution in the deaerator, the feed water inlet side where the feed water is introduced has a low temperature region. In order to meet this temperature distribution, a sufficient amount of heated steam is supplied to the low temperature region, and a relatively small amount of heated steam is sent to the water supply in other areas.

A concrete embodiment will be described with reference to FIG. Dissolved oxygen concentration meter 13 and thermometer 14 in the shell 1
The signal from is taken into the regulator 15. Adjuster 15
Is composed of a measurement signal AD converter, an arithmetic unit such as a control computer or a general-purpose computer, and an output signal converter. Moreover, the pressure measurement value or the pressure setting value in the shell 1 is taken into the controller 15, and the saturation temperature of water with respect to the pressure is calculated. Shell 1 detected in an area
The difference between the water temperature and the saturation temperature is calculated. If the water supply temperature is lower than the saturation temperature by more than the specified tolerance,
An opening signal is sent to the control valve 16 so that the maximum steam flow rate flows.

On the other hand, when the feed water temperature in a certain region is substantially equal to the saturation temperature within the allowable value, the manipulated variable of the steam flow rate in that region is determined by the measured value of the dissolved oxygen concentration. A change pattern of the dissolved oxygen concentration as shown in FIG. 9A is stored in advance in the controller 15, and the detected dissolved oxygen concentration is at any level ((1) to (1) in FIG. 9A).
Depending on whether it is in (8), the amount of steam blown out is shown in FIG. 9 (b).
(1) to (8) or (1) to (8) in FIG. 9C.
It is decided like.

The steam flow rate pattern of FIG. 9 (b) is designed to supply the maximum steam flow rate in the vicinity of the feed water inlet 2 so that the feed water temperature can be quickly raised to the saturation temperature. Further, the steam injection amount pattern of FIG. 9C is for uniformly supplying steam to each control valve 16 when the dissolved oxygen concentration at the water supply inlet 2 is equal to or higher than a certain value. In any case, when the dissolved oxygen concentration at the feed water inlet 2 is already below a certain value ((6) to (8) pattern), the phenomenological stability of the steam blowing portion is maintained (flow failure due to vapor condensation). To prevent a stable phenomenon), keep the lower limit of steam flow rate and shut off the steam supply in order from the most downstream side.

As described above, when the method for controlling the heating steam flow rate of the degassing apparatus of the present invention is used, since the steam flow rate is sufficient to degas to a predetermined dissolved oxygen concentration, wasteful consumption of heating steam is prevented. be able to.

FIG. 10 shows an example of the starting method. This is a method in which a large amount of process steam is sent at the feed water inlet side to heat the feed water that greatly falls below the saturation temperature when the deaerator is activated, and a relatively small amount of process steam is sent at the feed water outlet side.

After the deaerator has been operated for a certain period of time, the dissolved oxygen concentration and temperature show stable values, which means that degassing can be performed with a smaller amount of process vapor than during rated operation and during startup. As a result, the process steam required for heating the feed water can be greatly reduced on the feed water outlet side.

Another embodiment will be described with reference to FIGS. 11 and 12. These two embodiments apply the deaerator according to the present invention to a condenser of a power plant.

In FIG. 11, a bubbling nozzle 5 is provided so as to supply the heated steam to the condensate that has flowed into the water storage section 4 in the hot well 17 to bring it into contact therewith. The baffle plate 12 forming the meandering flow path 11 is arranged so as to match the bubbling nozzle 5.

In FIG. 12, the meandering flow path 20 is formed by two circular baffle plates 21a and 21b arranged concentrically with the condensate inlet 18 and the condensate outlet 19.

[0037]

As described above, according to the present invention, the meandering flow path is formed so that the feed water sent to the water storage portion in the shell comes into contact with the heating steam blown out from the through hole of the nozzle according to the route determined to the feed outlet. Therefore, the dissolved oxygen concentration of the feed water gradually decreases at each part of the flow path, and it can be reliably reduced to the required concentration or less in a short time.

Therefore, according to the present invention, there are excellent effects such that the deaeration performance is kept good, the process steam is not wastefully used, and the boiler start-up time can be greatly shortened.

[Brief description of drawings]

FIG. 1 is a sectional view showing an embodiment of a deaerator according to the present invention.

FIG. 2 is a characteristic diagram showing a dissolved oxygen concentration distribution of feed water.

FIG. 3 is a sectional view showing another embodiment of the present invention.

FIG. 4 is a sectional view showing another embodiment of the present invention.

FIG. 5 is a sectional view showing another embodiment of the present invention.

FIG. 6 is a sectional view showing another embodiment of the present invention.

FIG. 7 is a characteristic diagram showing a water supply temperature distribution.

FIG. 8 is a block diagram showing details of the regulator shown in FIG.

FIG. 9 is a graph showing a steam injection amount pattern incorporated in a regulator.

FIG. 10 is a diagram for explaining an example of a starting method of the present invention.

FIG. 11 is a sectional view showing another embodiment of the present invention.

FIG. 12 is a sectional view showing another embodiment of the present invention.

FIG. 13 is a sectional view showing a conventional deaerator.

[Explanation of symbols]

 1 ………… Shell 3 ………… Sprayer 4 ………… Water storage part 5 ………… Bubbling nozzle 11 ………… Meandering flow path 12 ………… Baffle plate 13 ………… Oxygen concentration meter 14 ………… Thermometer 16… …… Control valve 17 ………… Hot well

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Katsuya Oi 4-4, 2 Suehiro-cho, Tsurumi-ku, Yokohama-shi, Kanagawa Toshiba Corporation Keihin Office

Claims (4)

[Claims] 1. A jetting means comprising a plurality of nozzles having a large number of through-holes communicating with a steam header, wherein each through-hole of the nozzle faces a water storage part in a shell so that the steam header is connected to the nozzle. In a deaerator configured to eject the heated steam to be injected into the feed water through the through hole, the feed water sent to the water reservoir comes into contact with the heated steam blown out through the through hole of the nozzle according to a route determined to the water supply outlet. A deaerator characterized in that a meandering flow path is formed as described above. 2. The deaerator according to claim 1, wherein the meandering flow path is formed by using a plurality of baffle plates. 3. The baffle plates are arranged along the extending direction of the nozzle so that the water supply flows in parallel with or in parallel to the bubbles of the heating steam blown out from the through hole of the nozzle. The deaerator according to claim 2. 4. An oxygen concentration meter for detecting the dissolved oxygen concentration and temperature of the feed water is provided at each part of the meandering flow path, and during deaeration, the feed water temperature detected in each region and the shell device internal pressure obtained by calculation 2. The deaerator according to claim 1, wherein the amount of heating steam blown out from the jetting means is adjusted according to the detected dissolved oxygen concentration when the difference between the saturated temperature and the saturation temperature is within the allowable value.